New Delhi, April 22 -- A new four-year air quality study has revealed alarming levels of particulate pollution across India's major urban centres.

The analysis by Respirer Living Sciences - a Delhi-based climate-tech startup - found that all 11 metropolitan cities monitored consistently breached the National Ambient Air Quality Standards for PM10 between 2021 and 2024, with pollution levels remaining stubbornly high despite various policy interventions.

The most severe conditions were observed in northern India, where cities like Delhi, Patna, Lucknow and Chandigarh recorded particularly dangerous air quality.

Delhi's Anand Vihar monitoring station measured PM10 concentrations of 313.8 micrograms per cubic metre in 2024, while Patna's ...